Throughout this specification the terms wireless LAN, WLAN, Wi-Fi™, IEEE 802.11 are used interchangeably unless otherwise noted. The term wireless access point, also referred to by its abbreviation AP, refers to a device that provides wireless access to a network, e.g. the Internet, a local area network (LAN), or a wide area network (WAN). An AP may or may not include functionalities of a router or a gateway, and may be an integrated part of such devices. SSID is an abbreviation for Service Set Identifier and refers, inter alia, to the name of a wireless network by which it can be distinguished from other wireless networks. A wireless repeater, or RP, is a device that extends the reach of the wireless network provided by an AP, using the same SSID. A repeater may operate on the same channel or on a different channel than the AP its reach it extends. A repeater may be connected with the AP via a wired or wireless link. A device implementing an AP may function as a repeater. The term mobile station, or MS, refers to a mobile device that can be wirelessly connected to an AP for accessing the network. The term association refers to the process of establishing a connection between a MS and a particular AP, and the term disassociation refers to the process of terminating the connection between a MS and a particular AP. Before a MS can associate with an AP it typically must terminate any previous connection with a different AP (disassociate), if applicable.
Mobility and roaming is a key issue in wireless networks, and users expect their tablet computers, laptops etc. to be connected to a network at any time. Like with a mobile phone users want to stay connected to the wireless networks while moving around. In the case of Wi-Fi™ networks and in IEEE 802.11 terminology, this means keeping the wireless interface of the mobile station associated with an access point, this mode of operation being referred to as infrastructure mode. In telecommunication networks, the association process is controlled by the network itself. In WiFi networks, however, decisions on associating with or disassociating from an AP are entirely left to the mobile station. Hence, a mobile station must scan potential channels to discover new access points and request association. Moreover, the interconnection network must react to these successive associations, by keeping bridging and routing tables up to date, or by allocating a new IP addresses for example. These procedures cause variability in the delays during mobility, degrading significantly the quality of service for constrained traffic, like voice over IP. Furthermore, since the mobility decisions are taken in the station, it is impossible to provide efficient resource management in the network of access points, for load balancing or interference mitigation.
Some wireless networks, notably WiFi networks, use repeaters for providing proper signal coverage in a larger area that cannot be covered by a single AP. However, active repeaters use and occupy a portion of the limited bandwidth of the shared wireless medium even if not needed, i.e. when no mobile station is associated with the repeater, since they transmit their SSID beacon signal and management frames at regular intervals. The narrow frequency band around 2.4 GHz is shared between various wireless networks including IEEE 802.11 wireless LAN, IEEE802.15 Bluetooth and the like, and is relatively crowded. The 5 GHz band is larger and provides more alternative channels that can be used, but devices operating in this frequency band are less common as of today, and the range of a 5 GHz connection is typically smaller than that of a 2.4 GHz connection, mostly due to higher signal attenuation. As such, it is desirable to avoid unnecessarily using the limited shared resource whenever possible. In addition, an active repeater consumes power, and it is generally desirable to reduce the power consumption of devices when they are not used.